The provision of two parallel windshield wiper blades secured on a single windshield wiper driving arm is well known in the art.
U.S. Pat. No. 2,158,254 discloses a windshield wiper provided with two or more wiping elements, each of which are separately mounted to the vehicle at two spaced pivot points proximate the windshield, and which are powered by separate motors integral with the vehicle's electrical system. The wiper elements move across approximately the same area of the windshield surface but move in different or intersecting paths so that streaks which may be left by the first wiping element will be wiped off by the second wiping element which follows closely behind the first but which moves along a different path. The two wiper elements are, however, connected to each other by a link which restricts their movement back and forth and which limits the area of the windshield over which the wipers pass.
U.S. Pat. No. 2,605,491 teaches a windshield wiper comprising two wiper elements spaced apart and arranged parallel one another on a cross-head bracket which is in turn connected with the free end of an operating arm having a pivotal center. The wipers are arranged on the cross-head bracket such that the overall length of arcuate sweep of the wiper elements is increased in an attempt to clear the maximum area on the windshield. The wiper elements are, however, attached to the cross head brackets by a swivel which does not limit the rotation of the wipers thereon. As such, the wiper elements are left to randomly shift on the swivel as the operating arm moves back and forth across the window. As a result of the swivel attachment and resulting random shifting of the wiper elements, large areas of the windshield are often neglected. Additionally, the swivel attachment is prone to becoming stuck, thereby fixing the wiper elements in a single position.
In U.S. Pat. No. 2,607,944 discloses a combination windshield wiper for cleaning the surface of a windshield and which comprises a pivotally mounted reciprocating wiper arm with a wiper mounted in operative position on the outer end thereof, and a second wiper mounted opposite the first wiper and attached to the end of a telescoping rod wherein the outer end of the second wiper is provided with rollers adapted to travel within the groove of a track along the top edge of the windshield. The rollers may, however, become stuck within the groove of the track thereby preventing the wipers from moving across the windshield.
U.S. Pat. No. 3,874,019 teaches a windshield wiper driving arm having an adapter for mounting two parallel wipers on a single windshield wiper driving arm for providing improved cleaning of a windshield. The adapter being configured to allow total arm pressure to be divided substantially equal between the two wiper blades during wiping. This device, however, permits wiping in only a fixed area of the windshield.
In U.S. Pat. No. 4,553,283, there is disclosed a windshield wiper adapter provided with two windshield wiper blades attached thereto, and which tilts the wiper blades in the sweep movement direction as the wiper blades are swept across the surface of a windshield. This device, however, permits wiping in only a fixed area ofthe windshield and requires complicated adjustments to the adapter to control the tilting of the wiper blades.
Thus, there is a need for a windshield wiper attachment apparatus which provides improved wiping ability over a large area of a windshield, which is inexpensive, as well as simple to attach and adjust. Additionally, there is a need for a windshield wiper attachment apparatus which is easily replaceable, which does not require any electrical wiring or additional connection to the vehicle, and which overcomes the problems inherent in the prior art.